<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var score=parseInt(prompt('请输入成绩')/10)
        switch(score){
            case 10:
            case 9:alert('A');
            break
            case 8:alert('B');
            break
            case 7:alert('C');
            break
            case 6:alert('D');
            break
            case 5:
            case 4:
            case 3:
            case 2:
            case 1:
            case 0:alert('E');
            break
            default: alert('请输入0-100之间的数字')
            

        }
    </script>
</body>
</html>